The Influence of Filler Shape on the Microwave Absorptions of Polyethylene Composites with High Ferroalloy Powder Content

The ferroalloy powder (FeP) with remarkably high-magnetic permeability and high-temperature stability has attracted much attention for its potential application in the field of radar stealth. However, achieving high stealth performance in different frequency bands by controlling the shape of iron alloys remains a major challenge. Herein, FeP-filled high-density polyethylene composites with different FeP shapes by hot pressing are prepared. This work employs a straightforward vacuum hot-pressing molding technique to analyze the electromagnetic wave absorption property of composite materials utilizing two distinct forms of FeP as different fillers. It is noted that composites filled with 75 wt% spherical FeP with excellent impedance matching exhibit a minimum reflection loss (RL_min) of −60.75 dB at 12.23 GHz with a thickness of 2.55 mm, and a maximum effective absorption bandwidth of 8.31 GHz at 2.5 mm. While high-density polyethylene composites filled with 75 wt% flaky FeP obtain the RL_min value at a low frequency of 2 GHz because of the high magnetic loss. This work provides a guideline for developing applications of FeP-filled composites with different shapes.